1. Field of the Invention
The present invention relates to a self-emitting flat panel type display device, and particularly relates to a display device using thin film type electron source arrays.
2. Description of the Related Art
An FED (Field Emission Display) using micro cold cathodes that can be integrated is known as one of self-emitting flat panel type display devices using thin film type electron source arrays. The cold cathodes of FED are categorized into field emission type electron sources and hot electron type electron sources. The former includes Spindt type electron sources, surface conduction type electron sources, carbon-nanotube type electron sources, and the like. The latter includes thin film type electron sources of an MIM (Metal-Insulator-Metal) type comprised of a metal-insulator-metal lamination, an MIS (Metal-Insulator-Semiconductor) type comprised of a metal-insulator-semiconductor lamination, a metal-insulator-semiconductor-metal type, and the like.
As the MIM type electron source, for example, an MIM type electron source disclosed in JP-A-7-65710 or JP-A-10-153979 is known. As the metal-insulator-semiconductor type electron source, an MOS type electron source reported in J. Vac. Sci. Technol. B11(2) p. 429-432 (1993) is known. As the metal-insulator-semiconductor-metal type electron source, an HEED type electron source reported in High-Efficiency-Electro-Emission Device, Jpn. J. Appl. Phys., Vol. 36, p. L939 or the like is known, an EL type electron source reported in Electroluminescence, OYO-BUTURI, Vol. 63, No. 6, p. 592 or the like is known, or a porous silicon type electron source reported in OYO-BUTURI, Vol. 66, No. 5, p. 437 or the like is known. Incidentally, the MIM type electron source is disclosed in each of those documents.
FIG. 1 is a view for explaining the structure of an MIM type electron source and the principle of operation thereof. In FIG. 1, the reference numeral 11 represents a lower electrode; 13, an upper electrode; 12, an insulating layer; and 23, a vacuum atmosphere. In the vacuum atmosphere, a driving voltage Vd is applied between the upper electrode 13 and the lower electrode 11 so as to set the electric field in the insulating layer 12 to reach about 1-10 MV/cm. In this event, electrons e− near the Fermi level in the lower electrode 11 penetrate a barrier due to a tunneling phenomenon, so as to be injected into a conducting band of the insulating layer 12 as an electron accelerating layer. Hot electrons formed thus flow into a conducting band of the upper electrode 13. Of the hot electrons, ones reaching the surface of the upper electrode 13 with energy not smaller than a work function φ of the upper electrode 13 are released to the vacuum 23.
It is desired that thin film type electron source arrays applied to a display device or the like can be manufactured with a simple structure and in a simple process in order to attain reduction in cost. A photolithographic method (also referred to as a photo-etching method) is conventionally used for processing thin film type electron sources. However, an exposure device used in a photolithographic process (also referred to as a photo-process simply) is expensive. In addition, associated processes required before and after the photolithographic process, such as coating with resist, pre-baking, exposure, development, post-baking, removing, and cleansing, are long, and the process cost thereof is high.
In contrast, if resist can be printed by screen printing or the like, the cost of the manufacturing apparatus can be reduced. In addition, since the resist can be patterned directly, the processes required before and after the photolithographic process, such as coating, pre-baking and development, can be omitted so that the process cost can be reduced. However, the resist patterning accuracy using the printing method is incommensurably lower than the accuracy using the photo-etching method. Thus, there is a problem in application of the printing method to processing of conventional thin film type electron sources.
When a pattern involving the accuracy of pattern matching in only one lengthwise or crosswise direction is used, the processing accuracy in the resist patterning can be loosened and the printing method can be applied easily in comparison with a pattern involving the accuracy of pattern matching in both the lengthwise and crosswise directions. In the present invention, such a shape involving the accuracy of pattern matching in only one direction is referred to as “stripe shape” in the sense that the shape needs accuracy in only one dimension. In addition, an electrode having a stripe shape pattern is referred to as “stripe electrode”. That is, the stripe electrode is a linear electrode having a width with a structure having no hole, no convex portion, no concave portion, no curved portion, etc. intentionally formed in the electrode.
Particularly, when a printing method such as screen printing, dispenser printing, inkjet printing or transfer printing is used as the patterning method, the stripe electrode is preferred because the stripe electrode is a little affected by deterioration of the patterning accuracy caused by stretch of a screen, a blur of printed resist, or the like.